This invention relates to rotary molding machines, and more particularly to continuous injection molding machines for manufacturing thermoplastic products.
The prior art discloses a number of injection molding machines of the rotary type, including the continuous injection variety as described, for example in U.S. Pat. Nos. 3,833,329; 3,888,615; 3,888,616; 3,888,619 and 4,186,161. The machines disclosed in these particular patents, however, have the disadvantage that they are extremely costly to design and manufacture. Although they can be made with any desired number of molding assemblies or work stations that are repeatedly operable to mass produce a given, molded part, such machines otherwise are not readily convertible to produce other parts, nor are they themselves capable of being mass produced. Moreover, these prior machines tend to be rather inefficient, since their die cavities are designed to be supplied with an excess amount of potting or molding material, which must be separately withdrawn and discarded following each molding operation of a die. The act of separating the excess material from the molded part is a more complex operation. Also, the molds are usually difficult to service and repair.